Weighted Average Bed Temperature

The effect of even higher benzene levels has been studied on a demonstration plant scale a feed of 15 wt.-% benzene and 85 wt.-% n-C5 was completely saturated at a liquid hourly space velocity of 4 h 1 and a pressure of 30 bar at a weight average bed temperature (WABT) as low as 120°C (3). 

After we enter the feedstock information, we must define operating temperatures and associated process variables. We enter the Reactor Control section and define the operating temperature of each bed. There are two ways specify reactor inlet temperature. In the first method, we enter the weight-average inlet temperature (WAIT) for all the reactors and specify a bias for each reactor. In the second method, we enter a reactor reference temperature and specify a bias for each reactor. We use the second method to accurately fix the inlet temperature of each bed. We recommend this method when running the model for the first time. This ensures that inlet temperatures are accurate for the purposes of calibration. We show how to input the reactors temperatures in Figure 5.58. 

The reactor used by Kizer and simulated in this work is illustrated in Figure 1. It consists of a fluidized bed preheater section feeding directly the fluidized bed reactor section. Each section was a 0.4 m high cylinder of 0.184 m diameter. The preheater contained sand and was heated by an external electrical element. The FB203S catalyst is a powder of 0.173 mm diameter particles (weight average) and has a minimum fluidization velocity, of 0.021 m at normal temperature and pressure. 

W. C. Heraeus GmbH Co. KG, 381 WATB. See bed, weighted average temperature... 

The BP process [7] is based on a sand fluidized-bed pyrolysis reactor. The cracking temperature is kept at 400-600°C. Low-molecular hydrocarbons can be obtained. The process mainly involves converting waste plastics into normal linear hydrocarbons, the average molecular weight of which is 300-500. Most plastics can be treated by this process. Polyolefins are decomposed into small molecules with the same linear structure. PS is converted into styrene monomers and PET into mixture of hydrocarbons, carbon monoxide and carbon dioxide. A maximum of 2% PVC is allowed in this process, and the content of chlorine in the products is lower than 5 ppm. The distribution of alkene products in this process is like that in petroleum pyrolysis. The BP process was industrialized in 1997. 

Under typical conditions of 290°C spinning temperature, the molten viscosity is ca 200-2000 Pacs (2000-20,000 P) depending on average molecular weight. This is extremely viscous—similar to hot asphalt. The pump must provide a pressure of 10-20 MPa ( 100-200 bar) to force the flow through the pack, which contains filtration media (eg, a sand bed) to remove any particles larger than a few micrometers. 

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